The field of the disclosure relates generally to gas turbine engines and, more particularly, to oil cooling systems for a gas turbine engine.
Gas turbine engines, such as turbofans, generally include an oil system that distributes engine oil used to cool and lubricate components within the gas turbine engine. As turbofan engines become larger, faster, and more powerful, more heat within the engine oil needs to be dissipated, thus increasing cooling requirements of an oil cooling system that facilitates extracting heat from the engine oil.
At least some known oil cooling systems include heat exchangers that are positioned within a bypass duct that draws a fan stream air therethrough for turbofan propulsion. Oil is channeled through the heat exchangers where the fan stream air is used as a coolant and heat is transferred from the oil to the fan stream air. However, some heat exchangers are known to create drag within the fan stream air which decreases turbofan engine efficiency. Moreover, during turbofan engine low speed conditions, such as ground operating conditions, the fan stream air drawn through the bypass duct is low or not-present, decreasing the effectiveness of the heat exchangers. Furthermore, dedicated oil cooling systems for engine low speed conditions increase the weight of the turbofan engine, which also decreases overall efficiency.